Eli Lilly & Co's longtime Chief Executive John Lechleiter will undergo surgery next Monday for a dilated aorta, but is expected to make a full recovery from the potentially dangerous condition and return to work this summer, the drugmaker said on Monday. Lilly Chief Financial Officer Derica Rice, 48, will assume the additional role of acting CEO during Lechleiter's surgery and recovery period, the Indianapolis drugmaker said. Lechleiter, 59, had no symptoms of the condition, but learned of it during recent unrelated medical testing, Lilly said. Rice and Lechleiter have worked closely together over the past four years in formulating plans to revive Lilly's earnings and sales after ongoing generic competition for some of its biggest drugs, including its Zyprexa schizophrenia drug.